Board Game Arena is a webbrowser-based platform for online multiplayer tabletop gaming, which also hosts a lot of hanafuda games.
The web service is usable on both PC and mobile devices. Android also has a dedicated app. It is one of the most international places to play hanafuda games online, with crowdsourced translations in dozens of languages, and active players from North America, Europe and Asia.
Links to the game pages of each hanafuda game on the site.
Each includes an interactive tutorial, which is also playable for non-members. An account is needed to play a game. Both real-time and asynchronous (“turn-based”) play are supported.
The service has no ads. There are Premium subscriptions available that come with various perks. Some games have some restrictions for non-Premium members (always requiring at least one Premium member to take part in each match), but this is not the case for any hanafuda game.